Chemicals like histamine and acetylcholine bind to receptors and trigger blood-vessel changes and muscle contraction. Bovet designed synthetic molecules that plug those receptors and produced the first antihistamine drugs. These medicines not only suppress allergy symptoms but also prevent vasodilation and bronchial constriction. He then modified curare-like substances to create muscle relaxants that could be used safely during surgery. This advance transformed anaesthetic practice and enabled more complex operations. The idea of receptor antagonism became a cornerstone for later drugs such as antihypertensives and anti-ulcer agents. Bovet’s work helped establish the field of molecular pharmacology.

In the 1930s the physiological role of histamine was known but no selective blocker existed. Working at the Pasteur Institute, Bovet synthesized hundreds of diphenyl compounds and screened them on guinea-pig trachea and canine vessels to find molecules that selectively inhibited histamine responses. By quantifying efficacy and side-effects he introduced the modern idea of drug selectivity. Antihistamines went on to be used not only for rhinitis and urticaria but also as pre-anaesthetic agents and antimotion-sickness drugs. Bovet next investigated curare derivatives that competitively block acetylcholine receptors at the neuromuscular junction, paving the way for non-depolarising muscle relaxants. These studies provided early models of structure–activity relationships and ligand-binding assays, streamlining drug discovery. The receptor-antagonist strategy later underpinned β-blockers, ACE inhibitors and many other modern medicines. Bovet’s work redefined the chemical control of biological signalling, bridging medicine and chemistry.

Bovet extended Ehrlich’s receptor theory and quantified competitive antagonism using Schild plots. He examined substituent effects in diphenylmethyl-piperidine derivatives and demonstrated that H1-receptor selectivity correlates with pKa and hydrophobicity. pA2 values obtained on guinea-pig ileum produced linear Schild relationships, allowing the first numerical link between receptor occupancy and functional response. He also showed that the high lipophilicity of first-generation antihistamines explains their blood–brain barrier penetration and sedative side-effects. In neuromuscular studies he identified the role of quaternary ammonium groups in conferring high affinity to the α-subunit of nicotinic acetylcholine receptors and confirmed end-plate potential suppression electrophysiologically. His structure–activity work foreshadowed modern QSAR and drove ligand-oriented synthesis. By modelling the nonlinear relation between antagonism and vascular resistance in animal haemodynamic studies he introduced mathematical pharmacology into efficacy assessment. These contributions accelerated the clinical adoption of non-depolarising muscle relaxants and sharply reduced surgical mortality. Bovet’s insights remain foundational to today’s toxicity-minimisation strategies and target-based drug design.